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I have read and even been told by one mechanic that after 100000 miles you should not do a transmission fluid change. You know drop the pan replace the filter etc. Never a flush for sure. Any thoughts on this?
 

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The overall idea is that normal running transmissions will have some clutch material 'grit' built up in the fluid, which generally just helps engage each gear in normal operation. If there's no issue requiring repair (burnt fluid, slipping, banging, etc.), changing the fluid or flushing out this 'grit' would only serve to reduce the effectiveness of higher mileage clutch packs. Even changing the filter is going to drain ~8qts of the 12-13 total, and essentially become fairly fresh fluid on a used transmission (not as thorough as flushing, but some of the same thing). You can see my YouTube 'Part 2' video in my "Bad Grandpa" post for some footage of that draining.

In general, I just check my fluids, and if it's not causing an issue, drive it and just monitor levels/operation. I recently upgraded my pan and cooler on my Regal, and actually hated that I was removing majority of the 50k fluid and filter from a perfectly working race build with discontinued Raybestos Blue Plates (my drain pan wasn't clean enough to re-use the fluid, anyway). I'll be loading some fresh Dexron VI (eBay find) and monitoring from there, but that's just my latest anecdotal story. My dad (built this and many bigger race transmissions for decades) advised basically what I'm relaying, and actually wanted me to leave it alone, except knew I needed better cooling, so it was unavoidable.
 

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Guess I'm too old school......maybe because I've been in auto service industry for longer than most of the people on this site........not slamming anyone...... it's just what has been tried and true for a very long time. Generally in the auto service industry it is recomemded 30,000 to 50,000 miles. The 30K is meant more for heavier usage and the 50K for more average drivers. MY personal recommendation would be to go with 30K for normal usage.... Fresher/cleaner ATF is better for the internal parts in an auto trans. The trans fluid filter should also be replaced when doing an ATF fluid change.
My 2 cents.....Mr goodwrench(jake) PS, there is bound to be some clutch material in the trans fluid but there should not be a LOT. Generally the trans filter picks up most of normal wear and tear residue. As always, replace the filter when doing a fluid change.......
 

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If your 4T65e trans needs fluid at 30-50k, it's either heavily abused or dying. These aren't TH350/400's or C4/6's that got ridden heavy & needed fresh grip, they're actually well-designed for their (stock) use, given proper driving habits and fluid cooling. The minimal "routine" clutch/band wear material is easily handled by the filter for 100-200k, as proven by millions on the road.
 

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Good maintainence is a great thing for automatic transmissions.......should you chose to do this...... Best of luck, Mr Goodwrench. As I mentioned a day or so ago, being in the service industry I am a bit over kill with maintainence. BUT, that is easier than having to do transmission repairs. And of coarse change the fluid and filter....Most will suggest 50K intervals.....or they should.... I do mine every 30K. Knowing the cost of auto trans repairs, I see trans mission servicing as an alternative to possible problems down the road. Hey, when you get this all done shoot us a note and let us know how it all went and how dirty or clean was the old transmission fluid?? Hope you don't see any METALIC MATERIAL in the pan or filter......
 

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I worked at SuperFlow on transmission testing equipment for a couple of years and worked beside Larry Schaffer (of Shaffer Shifter fame).

As Jake and dezldave above showed, there are a wide range of opinions on this question.

The best advice that rings true to me is:

1. Change the fluid and filter at regular intervals UNLESS it is old and has a lot of grit in it already. You can lose shift characteristics by cleaning out the grit, but at that point, the trans is probably worn quite a bit and longevity has been compromised. That one is a hard call.

2. A flush is always a bad idea because you can force debris into the shift solenoids and cause them to fail pretty quickly.

3. I prefer using a bucket to catch old fluid from the trans cooler on the radiator and replace it as it drains out. Just hook up a hose to the fluid feed line (usually the upper line) and run the car for maybe 30 seconds then top it off with what you lost until the fluid runs clean. This way, you are pulling fluid from both the pan and also through the torque converter for a complete fluid change. If you use that method, you can leave a somewhat used filter in place or afterward drop the pan and replace the fluid lost in that process.

4. Lastly, you could just drop the pan to change the filter and be left with a mix of old and new fluid (what was left sitting in the TC and cooler). This decision has more to do with how dirty the fluid is to begin with.

My 2 cents.
 

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The issue with providing advice on these forums is you're typically dealing with folks who aren't looking to devote a huge amount of time/effort/funds to the particulars, if they have any way of avoiding it. This results in having to give a binary "this or that" answer, because they're either going to do it or not, and pay close attention in the process or not.

Understanding the variety of conditions transmissions are in, especially this far out from their original builds (unless they've spent the money on a rebuild), means that it's a crap shoot until it gets to the point of failure. Discussions like this one hope to delay that as long as possible, and we can only toss out a small number of immediate remedies and hints for someone to take away. (I relate it to having to "speak Army" versus discussing something among scientists I usually work with in my USAF role, depending on assignment/deployment co-workers.)
 

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This is one of those subjects that pushes my button. I wouldn't even hesitate a second to change fluid at 100k AS LONG AS A FILTER IS DONE ALSO!!!! I have done flushes on cars with over 300k always do the FILTER!!! What kills a lot of trans off is the fluid is worn out- or scientifically- depleted and dirty. new fluid has a lot of detergent and additives that loosens up the dirt and gunk and can plug up the filter- which causes pressure issues and that eats the clutches/ burns them up. Modern transmissions adapt to worn fluid. that doesn't mean they do well with worn fluid it just means they're getting by with it. I bought a 200k lesabre for my daughter with only 1st and reverse. I did a fluid and filter change, drove around for 1/2 hour in town then dropped the fluid and filter again. I got it to shift again. the more it was driven the better it shifted. I am a firm believer that done correctly - with a filter changing fluid is not to be feared. flush without doing a filter on a high mileage trans= failure. most quickie lube places do not change the filter= failure. IF SOMEONE SAYS THEY CAN BACK FLUSH THE FILTER, run out of there. that only stirs up the debris deposited in the bottom of the pan. its like taking a shower and putting your dirty underwear back on.
 

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This is an example of anecdotal evidence, while the overall discussion is how long is a maintenance interval based on thousands of results, or failure modes based on equivalent issues and timelines.

This one can be talked to death, due to a complex item involving a variety of long-term wear parts, intermittent possibilities of solenoid/valve body/etc. issues, various unknown or unacknowledged driving/maintenance patterns, and so on.

Short answer doesn't exist for this. You can take precautions in hopes if avoiding the preventable issues, and still be bit by another. All we can suggest is those precautions, and take note of the original person's technical level, financial situation, vehicle goals, etc. The choose-your-own-adventure book on this type of thing has good and bad endings for people who do all this thinking, and none of it.
 

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My short answer is this CHANGE the FILTER and the FLUID at 100k. The grit theory is a B.S. wives tale as the grit would wear out the bearings and bushings.
 

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Using that as a blanket statement, sure, but saying that is a 100% way to have fluid be in your transmission is ignoring the overall functions for the sake of oversimplification.
 

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Its the tried and true. preventive maintenance vs reactive maintenance. electronic control of the transmission has extended the fluid change intervals but down to the heart of the matter its still hydraulic pressure that allows the vehicle to move. we can argue this all night. I've been a mechanic most of my life. The term "lifetime" fluid means they expect the fluid to last until the component fails. usually from depletion of the additives and dirt/ debris built up from not having the fluid changed. that is coming from having daily hands on experience. 100k for these transmissions is half the expected life. taken care of the true life is quite a bit higher. sure there can be failures but the gold standard is fresh fluid and filter is going to last longer than worn out fluid and a plugged up filter.
I don't know what you do for a real living but I'm in the business and most failure come from neglect, abuse and the occasional dirty mass airflow sensor reporting incorrectly causing lower than required line pressures!
 

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You keep saying worn* fluid, but that's not what the original question is about, just if it's worth changing/flushing/etc. It may be required, it all depends on someone experienced looking things over without the financial incentive of doing the repair/maintenance work.

Totally unrelated, but top-of-the-head resume, since you brought it up: I've been working on these cars specifically (~75-100 in-person) for almost 20 years, along with a few years in a normal shop, raced and built snowmobiles nationally since the 80's, crewed 2 NASCAR modified teams for a few years, attended GM's engineering school for a bit (cars & girl got in the way), and spent the last decade as an enlisted USAF scientist doing R&D, calibration, and analysis of CBRN things in various laboratories. I also have a dad and grandfather who've built more transmissions than I can count, for street, diesel, drag, and circle track vehicles, so some things were passed on from that realm.

(Mostly typed that so I can now copy-paste elsewhere if someone asks and I don't want to type it again. Not necessarily relevant, and I respect your personal experience as well. I just think it's better when everyone knows the other guy in a chat has some feathers in their cap, too.)
 
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If your 4T65e trans needs fluid at 30-50k, it's either heavily abused or dying. These aren't TH350/400's or C4/6's that got ridden heavy & needed fresh grip, they're actually well-designed for their (stock) use, given proper driving habits and fluid cooling. The minimal "routine" clutch/band wear material is easily handled by the filter for 100-200k, as proven by millions on the road.
How about the tried and true of good maintaince will give your trans a longer and more trouble free life???
Mr goodwrench.. On another note, call a local auto dealer and ask what they do for auto trans service.
 

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I worked at SuperFlow on transmission testing equipment for a couple of years and worked beside Larry Schaffer (of Shaffer Shifter fame).

As Jake and dezldave above showed, there are a wide range of opinions on this question.

The best advice that rings true to me is:

1. Change the fluid and filter at regular intervals UNLESS it is old and has a lot of grit in it already. You can lose shift characteristics by cleaning out the grit, but at that point, the trans is probably worn quite a bit and longevity has been compromised. That one is a hard call.

2. A flush is always a bad idea because you can force debris into the shift solenoids and cause them to fail pretty quickly.

3. I prefer using a bucket to catch old fluid from the trans cooler on the radiator and replace it as it drains out. Just hook up a hose to the fluid feed line (usually the upper line) and run the car for maybe 30 seconds then top it off with what you lost until the fluid runs clean. This way, you are pulling fluid from both the pan and also through the torque converter for a complete fluid change. If you use that method, you can leave a somewhat used filter in place or afterward drop the pan and replace the fluid lost in that process.

4. Lastly, you could just drop the pan to change the filter and be left with a mix of old and new fluid (what was left sitting in the TC and cooler). This decision has more to do with how dirty the fluid is to begin with.

My 2 cents.
As long as the transmission doesn't already have issues, a 4T65E transgo kit is great for these cars. I think it helps the transmission shift optimally to reduce wear. Also improves the shift quality greatly particularly 1-2 shift.
 

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As long as the transmission doesn't already have issues, a 4T65E transgo kit is great for these cars. I think it helps the transmission shift optimally to reduce wear. Also improves the shift quality greatly particularly 1-2 shift.
Years ago I put a RAMCHARGERS shift kit in my 03 GTP SC. When I did that trans shift kit it worked better than I was hoping for. Under normal driving it has a slightly harder gear shift(1-2-3 and OD). When I did my shift kit install, I chose to go with one step down from hard shifting. Didn't want to create any internal breakage from real hard shifting. In my case it shifts pretty smooth......but when I get on the throttle it has a nice FIRM shift but no HARSH/POUNDING shifts......didn't want to break anything in the tranny. It's been several years now and it still works MOST EXCELLENT with zero issues. On another note, I'm not sure if one can find a RAMCHARGERS SHIFT KIT or not. ( I bought my kit from 3800 PRO). I also do trans fluid changes after 30K. For me I like the idea that I'm helping out with the overall trans life. After all these years it still works flawlessly.

PS, I'm not fond of real soft shift points. In my opinion a bit firmer shift points will limit the amount of CLUTH and BAND wear(slippage) . Best of luck to all! Mr Goodwrench(Jake) Going on almost 55 years and still have my shop in WHITE BEAR LAKE MINNESOTA.....my son is running most if it now.....but I still go get in the way!! Best part is he's an excellent tech and has learned all the do's and don'ts. Bad part is he has a weakness for tools when our local SANP ON guy stops in!! Not exactly sure why cause I/we have a giant tool box with just about everything one could ask for....except for alignments. We also just put up two new hoists......on of the old ones was getting a bit wimpy. Traded that one in after a little dealing with snap on. We have three diagnostic scanners(snap on). Bout the only thing we don't have is an alignment machine. OH, I think we are one of the very few shops that has a brake lathe! Some times we do this for our customers instead of selling a set of rotors. OK...... I have said too much..... best of luck for all with your rides. OH, one last thing.....we were able to get my son's 73 camaro into the 10's at local tracks. BUT the track in Iowa is best because of good track and a pretty low altitude and dry air for the hot rods. Take care all!
 

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The shift kits vendors always offered for these cars are pretty simple & can be made for $15 at the hardware store with a couple shims, and some springs if they go that far, tacking on a filter change with some. The Transgo has some deeper parts, if it's installed during an overhaul, and starts fairly medium for general purpose. I did the DIY increase to the shims in my race transmission, which makes it pretty radical (chirps full M/T slicks at 50+ for 1-2 at track), so I may back it down this year with pressure tweaks, or even go back to Transgo-length shims.

A lot of us in the MN GP club would prefer
Cedar Falls near Waterloo, IA versus Rock Falls near Eau Claire, WI for a better track day. I was a big part of that club for 5-ish years around the metro ~15yrs back, when this platform was in its prime, so I'm betting I know a bunch of folks in any 3800 circle still there. Dated a girl from White Bear/Grant area that joined the fun back then. Made a bunch of good friends in MN that I'm glad I stayed in touch with.
 
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